Abstract
Assuming the initial molecular interactions in the resin infiltrated layer formation at a dentin surface, an interaction between type I collagen and 2-hydroxyetyl methacrylate (HEMA) was investigated using a chromatography and a calorimetry techniques. It was found that at lower HEMA concentrations, the collagen helix tended to dissociate and became less stable with increasing HEMA concentration. It was supposed that the internal hydrogen bonds that had stabilized the helix were exchanged with those between collagen and HEMA, which meant the binding of HEMA onto collagen. On the other hand, an excess of HEMA deprived collagen of water, leading to the shrinking of collagen and a rise of its denaturation temperature, at higher HEMA concentrations. At a balanced concentration of 30 wt%, HEMA might be taken up into collagen fibers most effectively, which is strongly supported by the previous experimental fact that the tensile strength at a dentin surface was the strongest when 30 wt% HEMA was applied (Suzuki and Nakai, 1993).
